export function MP(ak) {
  return new Promise(function(resolve, reject) {
    window.onload = function() {
        resolve(BMap)
    }
    if(!window.BMap){
        var script = document.createElement("script");
        script.type = "text/javascript";
        script.src = "http://api.map.baidu.com/api?v=3.0&ak=" + ak + "&callback=init";
        script.onerror = reject;
        document.head.appendChild(script);
    }
  })
}